I.
Title :
Aluminium
II. Date of Experiment :
Thursday, 12th November 2019 at 09.30-12.00
III. Purpose of Experiment :
Knowing the properties of aluminium and its compound
IV. Equipment and Substances
1. Equipment
- Porcelain Cup 1 piece
- Dropper Pipes 10 pieces
- Test tubes 10 pieces
- Glass funnel 1 piece
- Reaction Tube Shelves 1 piece
- Spirtus burner 1 set
- Beaker 250 ml 2 pieces
- Measuring Cup 1 piece
- Wood clamp 1 piece
- Spatula 1 piece
2. Substances
- NaOH 0.1M solution; 1 M; 2M Sufficiently
- 1M HCl Solution Sufficiently
- 0.1 Mg HgCl2 solution Sufficiently
- 0.1 M HCl solution Sufficiently
- Solution (NH4)2S Sufficiently
- 0.1 M Na2CO3 Solution Sufficiently
- Solution Al2 (SO4) 3 0.1 M Sufficiently
- Aquades Sufficiently
- Aluminum Plate Sufficiently
- Blue Litmus Paper Sufficiently
- Cotton Sufficiently
- Filter paper Sufficiently
- Rubbing paper Sufficiently
A.Answer of question
1. Explain the amphoteric properties of aluminum based on the experiments
you are doing!
Answer :
Aluminum hydroxide is an amphoteric substance which is capable
of carrying out a neutralization reaction either with acids or with bases
(more precisely, both with hydrogen ions and hydroxyl ions). For example
in experiments, i.e. [Al2(SO4)3] reacts with a strong base, NaOH, in rural 1
white precipitate Al(OH)3 forms according to the reaction:
Al2(SO4)3(aq) + 6NaOH(aq) 3Na2SO4(aq) + 2Al(OH)3(s)
After the addition of NaOH drop by drop continues until the white
precipitate dissolves again, indicated by the reaction equation:
Al(OH)3(s) + NaOH(aq) Na[Al(OH)4](aq)
This shows that aluminum in its compound, Al(OH)3, carries out a
neutralization reaction and shows its acidic properties. Then this solution is
added with 0.1 M HCl. Addition causes the formation of white precipitate
gelatin [Al(OH)3]:
Na[Al(OH)4](aq) + HCl(aq) Al(OH)3(s) + NaCl(aq) + H2O(l)
The addition of HCl is continued until the precipitate formed dissolves
again, the addition of HCl is continued and no changes occur.
Al(OH)3(s) + 3HCl(aq) + AlCl3(aq) + 3H2O(l)
This shows that aluminum in its compound, Al(OH)3, carried out a
neutralization reaction and showed its basic properties. The ability of
Al(OH)3 to neutralize reactions or can be acidic or basic if reacted with
strong bases and strong acids is the reason why Al(OH)3 is called
amphoteric
2. Write the equation for the reactions that occurred in the experiments
Answer :
Experiment 1
2Al(s) + 2NaOH(aq) + 6H2O(l) → 2Na[Al(OH)4](aq) + 3H2(g)↑
2Al(s) + 3HgCl2(aq) → 2AlCl3(s) + 3Hg (s)
Hg(s) + Al(s) HgAl(s)
Experiment 2
Test tube 1
2Al(s) + 2NaOH(l) + 6H2O(l) → 2Na[Al(OH)4](aq) + 3H2(g)↑
Test tube 2
2Al(s) + 2Na2CO3(aq) + 7H2O(l) 2Na[Al(OH)4](aq) + 3H2(g) + CO2(g)
Test tube 3
2Al(s) + 6HCl(aq) 2AlCl3(aq) + 3H2(g)↑
Experiment 3
Al3+(aq) + 3H2O(l) Al(OH)3(aq) + 3H+(aq)
Experiment 4
Al2(SO4)3(aq) + 6NaOH(aq) 2Al(OH)3(s) + 3Na2SO4(aq)
Al(OH)3(s) + NaOH(aq) → Na[Al(OH)4](aq)
←
Na[Al(OH)4](aq) + HCl(aq) Al(OH)3(s) + NaCl(aq) + H2O(l)
Al(OH)3(s) + 3HCl(aq) → AlCl3(aq) + 3H2O(l)
Experiment 5
Al2(SO4)3(aq) + 3(NH4)2S(aq) → 2Al(OH)3(s) + 3H2S(g) +
3(NH4)2SO4(aq)
Al(OH)3(s) + NaOH(aq) Na[Al(OH)4](aq)
3. Explain uses of aluminium
Answer :
- Aluminium is used in a huge variety of products including cans, foils,
kitchen utensils, window frames, beer kegs and aeroplane parts. This
is because of its particular properties. It has low density, is non-toxic,
has a high thermal conductivity, has excellent corrosion resistance
and can be easily cast, machined and formed. It is also non-magnetic
and non-sparking. It is the second most malleable metal and the sixth
most ductile.
- It is often used as an alloy because aluminium itself is not particularly
strong. Alloys with copper, manganese, magnesium and silicon are
lightweight but strong. They are very important in the construction of
aeroplanes and other forms of transport.
- Aluminium is a good electrical conductor and is often used in
electrical transmission lines. It is cheaper than copper and weight for
weight is almost twice as good a conductor.
- When evaporated in a vacuum, aluminium forms a highly reflective
coating for both light and heat. It does not deteriorate, like a silver
coating would. These aluminium coatings have many uses, including
telescope mirrors, decorative paper, packages and toys.
